Automated guided vehicle are used in a growing number of warehouses, factories and stores for automating objects handling tasks. Automated guided vehicle allows for increasing productivity and improving logistic management.
Examples of such automatic guided vehicle are automatic guided vehicles comprising a fork carriage with load bearing forks, also known as “forklift automated guided vehicles” or “automated forklifts”.
WO2012169903 describes an example of such automatic guided vehicle comprising                a fork carriage with at least one load bearing fork,        a propulsion drive system to propel the vehicle,        a sensor to acquire position data of objects located in a detection field of the sensor, and        a computer receiving position data from the sensor and controlling the propulsion drive system to automatically guide the vehicle.        
In environments such as warehouses, factories or stores, human intervention is usually required in addition to automatic operations, for instance to survey tasks or to perform additional tasks that cannot be completed by machines alone. The environments must thus be shared between human and automatic machines.
Safety for the human work force is fundamental n such shared environments and impose stringent requirements to the automatic guided vehicles.
Automatic guided vehicles must for instance be certified according to safety norms (e.g. NF EN ISO 13849-1) to be allowed to perform certain tasks in such a shared environment.
Such a certification process involves analysing the entire control chain of the vehicle, from the sensors to the propulsion drive system, in order to guaranty a low probability of incidents during the operation of the vehicle.
Sensors, in particular, are an essential part of the control chain and it is of utmost important to be able to guaranty, within known limits, that the sensors are functioning correctly or that defects in the sensors operation are identified in a short period of time.
Sensors having high safety properties are known, for instance sensors certified as having a “PLD” level of safety according to norm NF EN ISO 13849-1.
However, inherent design constraints, related in part to the implementation of safety modules in these sensors, restrict the minimal size of such sensors.
These sensors can thus only be mounted in limited locations on the vehicle.
In particular, such certified sensors cannot be easily integrated on the rear of automated forklift and in particular on the load bearing forks since there typical vertical dimension are bigger the side opening in pallets.
A consequence of this situation is that the authorized movements of automatic guided vehicle are usually limited in the rear direction (direction of the load bearing forks) to guarantee the safety of the human beings around the vehicle.
The instant invention has notably for object to mitigate those drawbacks.